An improved approach to power losses in magnetic laminations under nonsinusoidal induction waveform

It is shown that it is possible to accurately predict power losses in ferromagnetic laminations under nonsinusoidal magnetic flux by specifically considering the dependence of hysteresis, classical, and excess loss components (P_h, P_c, and P_e, respectively) on the magnetic induction derivative B˙. Basically, it is assumed, through generalization of experimental and theoretical results under sinusoidal induction, that P_h is proportional to the average value of the instantaneous induction derivative, P_c is proportional to the average value of the square of the instantaneous induction derivative, and P_e is proportional to the average value of the instantaneous induction derivative to the three-halves power. An analytical expression for total power losses under distorted flux is consequently worked out. Experiments are reported concerning grain-oriented, nonoriented, and amorphous laminations, with distortion introduced by a variable amount of the third harmonic flux component